Patent GB-507599-A (GB)
Title: Improvements in or relating to means for electrically welding metallic projections onto metallic tubes
IPC: B23K11/00
Filed: 1937-12-17
Abstract: 507,599. Welding projections to tubes. BABCOCK & WILCOX, Ltd. Dec. 17, 1937, No. 35024. Convention date, Dec. 28, 1936. [Class 83 (iv)] In electrically welding groups of projections, such as studs, to metal tubes, particularly in situ in a boiler, a portable apparatus having a number of electrodes is located in relation to the tube so that one electrode first welds a projection of one group, such projection then co-operating with the said electrode to position another electrode for welding a projection of another group. The apparatus, which is mounted on a base 101 and may be supported by a counterbalance, comprises a pair of jaws 108 for simultaneously welding a pair of diametrically opposite side studs such as 147, 148 in staggered rows, and two pairs of electrodes 135 for welding the intermediate staggered rows of face studs 149, 150, 151, 152 in pairs. The jaws are recessed at 109 to receive headed studs and are pivoted at 105 and operated pneumatically by a piston rod 121 connected to the jaws by links 115 and a pin 119 which travels in a slot 123 in the frame. The jaws are provided with renewable metallic inserts 110 and the upper faces are provided with insulation at 111-113 to prevent short circuits, the parts 112 having shoulders 114 so as to locate the jaws relatively to previously welded studs 147, before welding studs 148. The face stud welding electrodes 135 are carried by pneumatically operated piston rods 128 mounted in radial cylinder 126, 127 on the plate 102, the pistons and rolls being insulated from the cylinders and the ends 132 being connected to the current supply. The piston rods of the inner pair of electrodes 135, which weld studs 149. 151, pass through copper shoes 138. which are connected by copper connectors 141, 142 to the jaws 108. The hollow tips of these electrodes are secured to terminals 133 which may engage the shoes 138 to supply current to the jaws 108, but may be separated therefrom by removable fibre pieces 143 carried by hand operated stop bars 144 when the face stud apparatus is in operation. The outer pairs of electrodes 135 for welding studs 150, 152 are secured to terminals 134. One pair of side studs 147 are first welded by the jaws and the inner pair of electrodes 135 then operated to weld a pair of studs 149, the fibre pieces 143 being applied. The outer pair of electrodes 135 are then operated to weld a pair of studs 150. The apparatus is then lowered, the shoulders 114 locating the apparatus in position for welding a pair of studs 148, which in co-operation with the jaws then locate the apparatus for welding pairs of studs 151 and 152 in turn. Each cylinder is controlled by a separate hand operated valve for supplying air to one or other end of its piston. The jaws 108 and electrodes 135 are water cooled by circulating water from a supply connection 154 through a manifold 155 provided with connections 160 to the jaws 108 and connections 156, 157 respectively to the inner and outer pairs of electrodes 135, the return from jaws being through pipes 162 and from electrodes through hollow piston rods by pipes 165, 166 respectively.